Mizzz Foster 2018 HOMEOSTASIS Homeostasis Homeostasis BALANCE Homeostasis

Homeostasis • Homeostasis = BALANCE • Homeostasis is the ability of the body to maintain a relatively constant internal environment, regardless of environmental changes.

HOMEOSTASIS • Organisms need to maintain a balanced and stable: • Concentration of oxygen and carbon dioxide • p. H of about 7 • Concentration of nutrients and waste • Concentration of salts and electrolytes • Volume and pressure of extracellular fluid (water) • Volume and pressure of intercellular fluid (water) • Stable body temperature

HOMEOSTASIS TOO MUCH HOMEOSTASIS LEVELS TOO LITTLE Body retains too much water and swells. Increase blood pressure leads to heart attack and stroke Salt and electrolyte concentration (135 – 145 m. Eq/L) nausea, vomiting, headaches, confusion Enzymes denature and life sustaining chemical reactions cannot proceed at all. Brain damage especially in infants. Clogged arteries, increase stroke, heart attack. Early unset of puberty Hormonal problems (Females stop menstruation) Body Temperature (98 degrees) Body Fat (BMI 18. 5 – 24. 9) Life sustaining chemical reactions may slow down too much, body becomes sluggish and weak, unreceptive Loss of mental stability. Drop in body temperature. Hormonal problems. (Females stop menstruation) Chemical reactions slow down due to excess water. Brain and cellular swelling Water (varies) Dehydration, headache, nausea, Increase in body temperature Fatigue Toxin and poison build up in body if it is not eliminated Waste Indicates the organism is not getting enough food / nutrition Some vitamins and minerals are toxic in high amounts Vit C= nausea, diarrhea, stomach cramps Vit A= poison / birth defects Vitamins (varies by vitamin) Chemical reactions will not take place Vit A = night blindness Vit C = scurvy Vit D = rickets Vit K = blood does not clot

Homeostasis If an organism’s body is not tightly regulated, disease can affect the organism.

Not too heavy, not too thin • Women can not have too much fat or too little. It interferes with their hormones. • Women with too much fat AND too little, stop having their menses and lose their fertility. • Women need to have a balanced amount of fat to be healthy.

Vitamin C deficiency: Scurvy causes periodontal disease, muscle fatigue and aches, rash, diarrhea, vomiting.

Vitamin D deficiency: rickets • Malformation of bones due to vitamin D deficiency.

Homeostatic Control Mechanisms • Variable: The factor that has changed in the organism’s internal environment. • Receptor: structure / organ that monitors changes in the environment and sends information to the control center. • Control center: structure / organ that determines the set point for a variable, analyzes information, and coordinates an appropriate response. • Effector: structure / organ that carries out the response directed by the control center.

Negative Feedback Mechanisms • Most homeostatic control mechanisms are negative feedback mechanisms. • A negative feedback mechanism causes the variable to change in a way that opposes the initial change. • Both the nervous system and the endocrine system are important to the maintenance of homeostasis. • The goal of negative feedback mechanisms is to prevent sudden, severe changes in the body. • Example: Body temperature rises, so the negative feedback would attempt to lower it.

Example: Thermostat in a house will monitor temperature, if it gets to low, the water will begin to boil and heat up radiator. If the temp is too high thermostat will trigger the radiator to stop.

Body Temperature

Body Temperature • Hypothermia: Body temperature gets abnormally low, which results in a slow down of life sustaining chemical reactions. • Hyperthermia: Body temperature is too high which can possibly result in the denaturation of enzymes and possibly brain damage due to denatured neural proteins.

Blood pressure

Blood Glucose

Blood Glucose • Diabetes= Person’s body does not produce enough insulin in order to keep the blood sugar in check. Excess blood sugar in the veins can result in organ damage. • Hypoglycemia= Person’s body produces too much insulin and there is not enough blood sugar left in the veins which can cause damage to the organs because they do not have enough energy to continue functioning.

Osmoregulation

Osmoregulation • Overhydration = When the amount of salt and other electrolytes in your body become too diluted. Hyponatremia is a condition in which sodium (salt) levels become dangerously low. This is the main concern of overhydration. • Dehydration= The amount of water in the body has dropped below the level needed for normal body function due to the organism loosing more water then what is taken in.

Blood Calcium Homeostasis

Blood Calcium Homeostasis • A drop in blood Ca 2+ causes the parathyroid gland to produce parathyroid hormone (PTH), which has several effects: • Ca 2+ is released from bone. • Ca 2+ is reabsorbed in the kidney. • Kidney in turn activates Vitamin D, which promotes the uptake of Ca 2+ in intestines.

Positive Feedback Mechanism • A positive feedback mechanism causes the variable to change in the same direction as the original change, resulting in a greater deviation from the set point. • Positive feedback mechanisms typically activate events that are self-perpetuating. • Most positive feedback mechanisms are not related to the maintenance of homeostasis. • Example: A woman’s contractions increase as the baby presses against the cervix. This contractions will continue to increase until the baby is born.

Labor Contractions

Blood Clots for Tissue Repair